Inclined axis rotatable drum concrete mixing apparatus



Sept. 23, 1952 c. 1. LONGENECKER 2,611,591

INCLINED AXIS ROTATABLE DRUM CONCRETE MIXING APPARATUS Filed June 7, 1950 INVENTOR. Ukarles I. Longeneclren ATTORN E Z Patented Sept. 23, 1952 "UNlT-E'D s'rArss PATENT iorrrcs i: 2,611,551 f,

" INCLINED AXIS ROTATABLE ljRUhI I CONCRETE 'MIXINGi APPARA'IUS Charles. 'I. :Longenecker, Wauwatosa, Wis., as signonto Chain. :Belt Company, Milwaukem:

Wis.,acorporation of Wisconsin. i 1

Application June17, 1950, 'Ser ialNo. 166;639'

The'invention relates apparatus, and more especially to that type in which an internally bladed coniform mixing drum is mounted with its longitudinal axis inclined to the horizontal and is rotatable about such axis-by power means; the lower, larger end of the drum' being closed while its smaller, higher end is provided with an opening-through which the concrete materials may be charged into the drum'an'd/or discharged therefrom. Such opening has asuitable door or closure structure associated with it, adapted to beso positioned with respectto the opening during the mixing period as to-prevent escape of the materials from the drum, and to be shifted when themixinghas been completed topermi't the mixtureto be discharged through the opening.

The internal blades in general comprise helical 3 Claims. (CL: 259-437 5-) to batch concrete mixing 1 strip-like elements suitably secured'tothe drum shell with their outward edges abutting the inner surfacethereof, and uponrotationofthe drum they assist in'the comm'rngling oithe materials as well as serving'as screw conveyors which im-- part movement longitudinally or the drum to peripheral portions of the batch. When the ro tation of'the drum is in such direction that these blades move the mixture toward the materialtransfer opening'at the'smaller end of the drum, they effect the discharge of the batch when the door or closure structure is opened.

In some instances it is the practice to rotate these drums .inlthis direction during both the mixing and the discharge periods, in accordance with .'the disclosures of prior U. S. Patent No.

2,303,902. granted December 1,1942; but in many cases the direction of drum rotation is reversed during the mixing period, whereby the helical bladeswork the materials: toward the closed lower endof the drum. When operated in this manner considerable difiiculty has been experiencedin securing a completecomminglingof all of-the batch, for the blade action forces the-relatively any-appreciable relative movement between-its particles such as is necessary to effect mixing thereof. Little if any of the water introduced into the drum'is abl-to-penetrate" this mass,- and asaresult of the pressuresexerted'u-pon it, the mass'is compacted-intoa ball or layer which tends to' adhere to thedrumheadr If the drum' rotation is continuedin this direction throughout the normal-.mixing period,

. dry:unmixedaggregates,wholly unacceptable as a ccncrete mixture.

In an effort to. overcome this difiiculty, reversal of :theldirection of drum rotation several times duringst-he mixing .period is sometimes :resorted to, :and while this alleviates the condition to some extent, since it is volitional on'the part of the :operator: and therefore not always .followed,

it' affords". no reallysatisfactory solution to the problem;

The principal object of the: present invention is to provide 'a drum construction. for .this inclined axis type of 'mixer which will substantially eliminate the above described difl'iculty without the necessity for any unusual or voli tionalprocedure onrthepartof the operator. One form of .theinyention .is illustrated in the accompanying drawing forming apart of thisrspecification, in.- which like reference characters designate-like parts'inall the views, and in which:

.Figure'l is a longitudinal vertical-sectionalview oftazbatchqccncrete mixing drum of theinclined axisitype, constructed 'and arranged. in :accordance with the invention Fig. 2 is-aplan: view of the drum shown "in Fig. 1, withithe shell partly broken away'and in section; and V .iFig... -3-'is :a' cross sectional view, onap'proximately the-plane .indicatedby the line 3-3 in Fig..;1,ilooking iuthe direction of the arrows.

Referring to the said: drawing in. greater detail, the drum there shown is of the kind widely used in a well known inclined .axis mixing unit of the truckemounted type, but sincethe' framework oi-such; unit as well as the drumldriviug mechanism and. the door: or iclosure: structure vafor 1 the material-transfer opening of the drum are or may be conventional, and form no part of the invention, they have not been illustrated.

The drum comprises a coniform shell I I, the larger end of which is closed by a head structure 12 while its smaller end is open to provide the material-transfer opening [3 through which the concrete materials may be charged into and/or discharged from the drum. In practice the drum is rotatably mounted in a framework with its longitudinal axis 14 inclined to the horizontal at an angle of about as indicated in Fig. 1, whereby its smaller open end is'eleva'ted above its larger closed end; and the drum is rotatable in either direction about such inclined axis by a source of power and transmission mechanism connected to a sprocket I5 carried by the head structure l2. The water necessary for the batches of concrete is introduced into the drum through a water supply'pipe l6, passing through the forward bearing and the axial portion of the head [2, and custon'iarily provided at its inner end with a valved discharge nozzle, not here shown. Two or more helical blades ll are disposed within the drum substantially as shown, and rigidly attached to the inner surface of the shell in any appropriatemanner. Short auxiliary blades i8 and 19 also may be positioned in the larger end portion of the drum and secured to the shell ll and/or the head 12, to assist in the mixing action.

The central portion of the head structure 12 carries a deflecting member 20, comprising a hollow cone having its base welded or otherwise rigidly secured to the inner face of the head structure and its body surrounding that part of the water supply pipe I 6 which lies within the drum. This cone, extending rearwardly from the head into the zone of formation of the above-mentioned compacted mass of unmixed -materials, causes such mass to assume an annular form, or at least to be of reduced thickness in the axial portion of the drum, and facilitates the dislodgement and breaking-up of such mass in the manner about to be described.

This result is accomplished upon reversal of the drum rotation to discharge the batch, through the provision of a longitudinally extending supplemental blade 2i disposed in the larger end portion of the drum somewhat forwardly of the head l2 and inwardly of a pair of the blades I! and I8, from which it is supported by struts 22 and 23. As will be clear from the drawing, this blade 2! is set at an angle to the axis [4 of the drum, and its longitudinal edge portions 24 and 25 are angularly disposed with reference to its body portion. With the drum rotating in the discharge direction (indicated by the arrow in Fig. 3), the blade acts during its passage through the upper right-hand quadrant of its travel to lift portions of the concrete materials and discharge them forwardly toward the head l2 and against cone 20 for deflection thereby and impingement upon the adjacent layer or ball of compacted unmixed materials. Thus, at each revolution of the drum such compacted mass of materials in effect is subjected to a bombardment by partially or completely mixed materials from the central portion of the drum, which tends to dislodge and disintegrate the mass whereby it may be dispersed throughout and intermixed with the rest of the batch.

When these inclined axis mixing drums are operated on the two-direction or reversal principle, during rotation in the mixing direction (clock- 4 Wise as viewed in Fig. 3) the forward movement of the materials by the helical blades I! which piles said materials up in the forward end of the drum also causes the upper surface of the batch to assume a rearward slope, somewhat as indicated by the line 30 in Fig. l, and during this time the blade '21 is more or less completely buried in the piled-up materials. However, upon reversal of the drum rotation to the discharge" direction, whereby the blades I! move the mixture toward the rear or smaller end of the drum. even though the door controlling the opening H be not opened, there is an immediate tendency to reverse the direction of the slope of the upper surface of the batch, and thus portions of the blade 2! may emerge from the mixture at the highest point of blade travel, even before the discharge door is opened. The full action of the blade in bombarding the layer or ball of unmixed materials at the drum head takes place, however, only after a portion of the batch has been discharged, so that the blade may emerge from the materials completely. This begins early enough in the discharge operation for an appreciable portion of the batch to still remain in the drum into which the unmixed materials from the head end may be incorporated and produce an acceptable mixture.

As stated in said prior Patent No. 2,303,902, when drums of this type are uni-directionally operated in accordance with the teachings of such patent, compacting or balling of unmixed materials on the drum head is minimized or eliminated. However, since the present device functions during rotation of the drum in the direction called for by the said patient, it is obvious that this invention may be employed if necessary or desirable when operating on the uni-directional principle.

- What is claimed is: r

1. In concrete mixing apparatus of the class described, a drum comprising a perimetric wall surrounding a longitudinal axis of rotation which is inclined to the horizontal, and a head closing the lower end of said drum, the higher end of the drum being provided with a material-transfer opening; helically arranged mixing and conveying blades secured to and extending inwardly from said perimetric wall, adapted through rotation of the drum in one direction about said axis to move concrete materials in the drum from the lower end portion thereof upwardly toward said opening, and through rotation of the drum in the opposite direction to move such materials downwardly into said lower end portion and pile them therein to the full diameter of the drum, whereby intermixing of such materials is prevented and a compacted mass of unmixed materials may be for-med and maintained adjacent the head; and means for dislodging and disintegrating such compacted mass, comprising a supplemental blade member mounted within the drum adjacent the head and so disposed with respect to the drum axis as to lift portions of the materials when the drum is rotated in the first mentioned direction and discharge them in a longitudinal direction opposite to that in which the mass of materials is being moved by the helical mixing blades as a result of such rotation, whereby to impinge said lifted portions against the mass of unmixed materials compacted against the drum head.

2. In concrete mixing apparatus of the class described, a drum comprising a perimetric wall surrounding a longitudinal axis of rotation which is inclined to the horizontal, and a head closing the lower end of said drum, the higher end of the drum being provided with a material-transfor opening; helically arranged mixing and conveying blades secured to and extending inwardly from said perimetric wall, adapted through rotation of the drum in one direction about said axis to move concrete materials in the drum from the lower end portion thereof upwardly toward said opening, and through rotation of the drum in the opposite direction to move such materials downwardly into said lower end portion and pile them therein to the full diameter of the drum, whereby intermixing of such materials is prevented and a compacted mass of unmixed materials may be formed and maintained adjacent the head; a deflecting member carried by and extending from the drum head into the zone of formation of said compacted mass; and means for dislodging and disintegrating such compacted mass, comprising a supplemental blade member mounted within the drum adjacent the head and radially -inward of said helical mixing blades, said supplemental blade being so angularly disposed with respect to the drum axis as to lift portions of the materials when the drum is ro tated in the first mentioned direction and move such portions in a longitudinal direction opposite to that in which the mass of materials is being moved by the helical mixing and conveying from said perimetric wall, adapted through rotation of the drum in one direction about said axis to move concrete materials in the drum from the lower end portion thereof upwardly toward said opening, and through rotation of the drum in the opposite direction to move such materials downwardly into said lower end portion and pile them against said head to the full diameter of the drum, whereby inter-mixing or" such materials is prevented and a compacted mass of unmixed materials may be formed adhering to the head; a conical deflecting member carried by and extending from the central portion of the drum head into the zone of formation of said compacted mass; and means for dislodging and disintegrating sueh compacted mass, comprising a supplemental blade member mounted within the drum adjacent the head and extending longitudinally of the drum intermediate its axis and said helical blades, said supplemental blade member being so angularly disposed with reference to the drum axis as to lift portions of the materials when the drum is rotated in the first mentioned direction, impart motion thereto in a longitudinal direction opposite to that in which the mass of materials is being moved by said helical mixing blades as a result of such rotation, and discharge said lifted portions against said conical member for deflection thereby and impingement against the mass of unmixed materials compacted against the drum head.

CHARLES I. LONGENECKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,490,215 Hilkemeier Dec. 6, 1949 FOREIGN PATENTS Number Country Date 563,600 Germany Nov. 9, 1932 

